Technical Field
The present invention relates to a stamping or hydroforming die, and more particularly to a forming die with a flexible blank holder.
Related Art
To form a product of a complicated shape by cold stamping in the prior art, the clearances between the upper die insert and blank holder needs to be adapted, which generally requires three to ten days and thereby prolongs the process of product development.
In a conventional hydroforming die, an O-ring is used for sealing. However, abrasion and leakage may easily occur due to dramatically small contact area between the O-ring and the blank.
Moreover, as for the stamping or hydroforming dies, a punching forming die 10 in the prior art (shown in FIG. 1) is provided with an upper die set 11 and a lower die set 12 (having a lower die punch 121) which are in relative movement, and a metal blank holder 15 is placed between the upper die set 11 and the lower die set 12. In this way, forming by punching is implemented. However, in the forming process, a blank 14 needs to be tightly retained by the metal blank holder 15 and a metal upper die 13, and therefore, the blank may be easily cracked or scraped by forming, which requires extra time and cost for grinding and polishing the die.